Protectivity of Freeze Dried Inactivated Rift Valley Fever Vaccine

Background: Vaccinations for animals are crucial for food production, animal welfare, public health, and animal health. They are an affordable way to stop animal sickness, increase food production efficiency, and lessen or stop the spread of zoonotic diseases to humans. Animal vaccines that are both safe and efficacious are vital to modern culture. The vaccine should induce a strong, protective and prolonged immune response against the antigenic factor. In order to achieve these goals, novel vaccination techniques and an efficient adjuvant are required to render the vaccine immunogenically protective and trigger a strong immune response. Aim: Our study aims to promote and enhance the immunogenicity against RVF virus disease through lyophilized inactivated RVF vaccine through induction of early cellular, high and prolonged humeral immunity in vaccinated animals using cabopol as stabilizer and Saponin or normal saline as a diluent at time of vaccination. Moreover, manufacturing of these vaccines is easy to be done. Results: The gained results revealed that RVF freeze-dried vaccine with Carbopol that reconstituted using Saponin elicited better immune response than that reconstituted using normal saline (NaCl). The cell mediated immune response as represented by lymphocyte blastogenesis and phagocytic activity were markedly increased with high levels when we used Saponin as a diluent than that in group vaccinated with vaccine diluted with NaCl, on the other side the humeral immune response in group vaccinated using the Saponin as diluent is more detected and stayed within the protective level till the end of 11th month post vaccination (1.5 TCID50) while the immune response induced after using normal saline as a diluent stayed within the protective level till the end of 10th month post vaccination (1.8 TCID50). Conclusion: The use of Saponin as a diluent for reconstitution of the freeze dried RVF vaccine is preferable than the use of normal saline enhancing both sheep cellular and humeral immune response.

Modeling Rift Valley Fever with Treatment and Trapping Control Strategies

We consider a rift valley fever model with treatment in human and livestock populations and trapping in the vector (mosquito) population. The basic reproduction number R 0 is established and used to determine whether the disease dies out or is established in the three populations. When R 0 ≤ 1, the disease-free equilibrium is shown to be globally asymptotically stable and the disease does not spread and when R 0 > 1, a unique endemic equilibrium exists which is globally stable and the disease will spread. The mathematical model is analyzed analytically and numerically to obtain insight of the impact of intervention in reducing the burden of rift valley fever disease’s spread or epidemic and also to determine factors influencing the outcome of the epidemic. Sensitivity analysis for key parameters is also done.

Evaluation of the Factors Controlling Concentration of Non-Condensable Gases and Their Possible Impact on the Performance of Geothermal Systems: Case Study of Olkaria Wells in the Kenyan Rift Valley

The Olkaria geothermal field is located in the Kenyan Rift valley, about 120 km from Nairobi. Development of geothermal resources in the Olkaria area, a high temperature field, started in the early 1950s. In the subsequent years numerous expansions have been carried out with additional power plants being installed in Olkaria. These include a binary plant at Olkaria South West (Olkaria III) in 2000, a condensing plant at Olkaria North East (Olkaria II) in 2003, another binary plant at Olkaria North West (Oserian) in 2004 and finally condensing plants in the year 2014 within East production field (EPF) and Olkaria Domes (OD) areas. The total generation from this field is about 730 Mw. The study considered samples from 4 producing wells from 3 fields of the Olkaria geothermal area (OW-44 from the Olkaria East, OW-724A from the Olkaria North East, and OW-914 and OW-915 from the Olkaria Domes field). The chemical data were first analyzed using SOLVEQ. This helped in the determination of the equilibrium state of the system, the reservoir temperatures and the total moles to be run through CHILLER. The run CHILLER considered the processes that have been proven to be occurring in the Olkaria field i.e., boiling and condensing processes, fluid-fluid mixing rocks and titration resulting from water-rock interaction. The effects on gas evolution were evaluated based on the resulting recalculated gas pressures. The results indicate that the gas species are not in equilibrium with the mineral assemblages. The CHILLER evaluation shows boiling as the major process leading to the evolution of gases. OW-44 had the least gas concentrations, arising from the considered reservoir processes due to degassing, and near surface boiling, besides the removal of NH3, H2 and H2S are through the reaction with steam condensate. The gas breakout is most likely in OW-914 and least in OW-44. The study proposes different reservoir management strategies for the different parts of the Olkaria geothermal field. That is by increasing hot reinjection in the eastern sector around well OW-44. The reservoir around OW-914 is to be managed by operating the wells at a minimum flow rate (or even to close them) or the use of chemical inhibitors to prevent calcite scaling.

Model test study on the formation and development of underground erosion ground fissures in the Kenya Rift Valley

The Kenya Rift Valley is relatively prone to underground erosion ground fissures and associated disasters,which gravely hinder local engineering construction and economic development.In this research,we performed field and experimental studies on ground fissures in the Kenya Rift Valley area,and determined the structural characteristics of underground erosion fissures.Based on a geological survey of the area,we generalized a geological model for typical ground fissures and reproduced the intermediate process of ground fissure propagation using a large-scale physical model test.Further,the development process of underground erosion fissures were categorized into four stages:uniform infiltration,preferential infiltration,cavity expansion,and collapse formation stages.During the development of underground erosion fissures,water content was distributed symmetrically along the fissures,and these fissures acted as the primary infiltration paths of water.When the ground collapsed,the increase in negative pore water pressure was greater,whereas the increase in positive pore water pressure was less in the shallow soil;moreover,in the deep soil,the increase in positive pore water pressure was greater than that of negative pore water pressure.Additionally,the earth pressure increment initially increased and then decreased with the development of erosion.During underground erosion collapse,the water content and pore water pressure appeared to increase and decrease rapidly.These results can be employed to predict the occurrence of underground erosion ground fissures and the resulting soil collapse.

THE CHARACTERISTICS OF GEOLOGICAL GENERAL FIELD OF VOLCANIC BELT IN LANCANG RIFT VALLEY AND ITS SIGNIFICANCE FOR EXPLORATION

Based on the theory of dissipative structures and moving character-parameters of elements,this paper examines the characteristics of the geological general field of volcanic belt in the Lancang rift valley,west Yunnan,China-with an open system and lower pressure environment,the volcanic belt is characterized by a large scale continuously graduating dissipative structure and three orders of concentrated minerogenetic material fields,and by the energy fields that influence the time and space structure of material fields.The research shows that the third order minerogenetic material fields which surround volcanic eruptive centers and have hydrothermal superposition and reconstruction after the magma stage possess favorable prognosis targets for copper polymetal.

Modeling for Inter-Basin Groundwater Transfer Identification: The Case of Upper Rift Valley Lakes and Awash River Basins of Ethiopia

Groundwater movement beneath watershed divide is one component of the hydrological cycle that is typically ignored due to difficulty in analysis. Numerical ground-water models, like TAGSAC, have been used extensively for predicting aquifer responses to external stresses. In this paper TAGSAC code was developed to identify the inter-basin groundwater transfer (IBGWT) between upper Awash River basin (UARB) and upper rift valley lakes basin (URVLB) of Ethiopia. For the identification three steady state groundwater models (for UARB, URVLB and for the two combined basins) were first created and calibrated for the 926 inventoried wells. The first two models are conceptualized by considering the watershed divide between the two basins as no-flow. The third model avoids the surface water divide which justifies IBGWT. The calibration of these three models was made by changing the recharge and hydrogeologic parameters of the basins. The goodness of fit indicators (GoFIs) obtained was better for the combined model than the model that describes the URVLB. Furthermore, the hydraulic head distribution obtained from the combined model clearly indicates that there is a groundwater flow that doesn’t respect the surface water divide. The most obvious effect of IBGWT observed in these two basins is that it diminishes surface water discharge from URVLB, and enhances discharge in the UARB. Moreover, the result of this study indicates potential for internal and cross contamination of the two adjacent groundwater.

Cattle Feed Resource,Water Sources and Housing System in the Central Rift Valley of Oromia Regional State,Ethiopia

The study was conducted in Adami Tulu Jidokombolcha(ATJK),Bora,Dodola,Shala and Negele-Arsi districts with objective to assess main cattle feed resources,water sources and housing systems.A pre-tested,semi-structured questionnaire was used to conduct survey.About 240 respondents were identified using random sampling techniques.Collected data was analyzed by SPSS statistical software(Ver.24).Study result indicates that household in average had three hectares of land and allocated about two hectares of land for crop cultivation.Most respondents reported that cattle herding is not common during dry season while it is common during wet season.Survey result indicate that natural pasture,weed and maize tiller and stored crop residues are main feed resources in wet season while crop after math,crop residue and fodder trees are main resources during dry season.Brackish,local mineral and common salt are mineral sources for cattle in study areas.Lake,river and boreholes are important water sources in dry season where as ponds and rivers are main water sources during wet season for their cattle.The observed cattle watering frequency is mainly once a day.Housing system practiced in the study areas is mainly Kraal.The information generated from this study on land size per household,cattle herding system,feed resources,mineral sources,water sources,water utilization and housing type can be used as a baseline for any livestock development programs in those and similar areas.

Import of Rift Valley fever to China:a potential new threat?

Several recent studies in Virologica Sinica and other journals have highlighted the enormous international challenge of emerging arboviral diseases,such as Zika virus disease,dengue,and chikungunya(Islam et al.,2015;Maurice et al.,2015;Dai et al.,2016;Deng et al.,2016;Song et al.,2016;Wang et al.,2016;Xu et al.,2016;Zhang et al.,2016;Zhou

DYNAMICS OF A KIND OF RIFT VALLEY FEVER MODEL

A novel mathematical model of the epidemiology of Rift Valley fever (RVF) is studied, which is an ordinary differential equation model for a population of mosquito species and the hosts. A disease-free equilibrium is discussed as well as its local stability. The prevalence of disease is proved under some conditions. Finally the vertical transmission is considered in a model for such a mosquito population.

Land Use and Environmental Gradients Influence on Riparian Woody Plant Diversity and Structure in Lake Manyara Watershed Ecosystem, Tanzania

Riparian vegetations are important in supporting ecological connectivity between aquatic and terrestrial ecosystems. The structure and species composition of riparian woody plants have been subjected to multiple forces with varying degree of influences. This study examined the influence of land use and environmental gradient to the structure and composition of the riparian woody plants in northern Tanzania. A total of 270 plots were surveyed for woody plant species in the riparian ecosystems and later analysed to determine the influence of land use categories (homegarden, crop field, woodlot, open canopy forest, and closed canopy forest) and environmental variables (temperature, precipitation, elevation and slope) to the species richness, abundance, and stand parameters. Basal area was higher in woodlots, homegardens and crop fields than in the open and closed canopy forests;and as expected the reverse was true for the number of stocking density. Correlation among stand parameters with environmental variables varied significantly. Species richness and species abundance were negatively correlated to precipitation, temperature and elevation, while stocking density and basal area were positively correlated to precipitation. The study recommends continual retentions of trees on farm, further promoting of agroforestry interventions and sustainable utilization of woody plants in open and close canopy forests.

On Native Origin of the American Indians

There have been controversies over differing opinions in the source of the American Indians. In this paper, the writer criticized the so-called classical theory that the remote ancestors of the American Indians entered America from Asia through the Bering Straits 14,000 ~ 20,000 years ago, worn their “clothes” and carried kindling during the late Paleolithic, no matter how by “boat” across the Bering Sea or by foot through a “Bering Land Bridge” which might once link up Asia and North America during glacial period;and independently proposed a new hypothesis that American Indians might be originated from the Western Rift Valley of North America. On the basis of locus distribution of American ancient human’s remnants, the writer pointed out that American ancient humans might be first originated at Yukon Territory of Canada within the Western Rift Valley of North America (the Basin & Range Province), and then migrated south ward (Yukon Territory → Mojave Desert → Mexico → Peru → Chile). Moreover, American Indians would have long been a presence for 40,000 years, or even 100,000 ~ 200,000 years in the American continents. So far, the logical basis which American Indians came from Asia 14,000 ~ 20,000 years ago was crushed, and derived two inferences: 1) American Indians might be originated from the Western Rift Valley of North America;2) Only the Eskimo might be the mover eastward from Asia, because of their gene B.

Support for research towards understanding the population health vulnerabilities to vector-borne diseases:increasing resilience under climate change conditions in Africa

Background:Diseases transmitted to humans by vectors account for 17%of all infectious diseases and remain significant public health problems.Through the years,great strides have been taken towards combatting vectorborne diseases(VBDs),most notably through large scale and coordinated control programmes,which have contributed to the decline of the global mortality attributed to VBDs.However,with environmental changes,including climate change,the impact on VBDs is anticipated to be significant,in terms of VBD-related hazards,vulnerabilities and exposure.While there is growing awareness on the vulnerability of the African continent to VBDs in the context of climate change,there is still a paucity of research being undertaken in this area,and impeding the formulation of evidence-based health policy change.Main body:One way in which the gap in knowledge and evidence can be filled is for donor institutions to support research in this area.The collaboration between the WHO Special Programme for Research and Training in Tropical Diseases(TDR)and the International Centre for Research and Development(IDRC)builds on more than 10 years of partnership in research capacity-building in the field of tropical diseases.From this partnership was born yet another research initiative on VBDs and the impact of climate change in the Sahel and sub-Saharan Africa.This paper lists the projects supported under this research initiative and provides a brief on some of the policy and good practice recommendations emerging from the ongoing implementation of the research projects.Conclusion:Data generated from the research initiative are expected to be uptaken by stakeholders(including communities,policy makers,public health practitioners and other relevant partners)to contribute to a better understanding of the impacts of social,environmental and climate change on VBDs(i.e.the nature of the hazard,vulnerabilities,exposure),and improve the ability of African countries to adapt to and reduce the effects of these changes in ways that benefit their most vulnerable populations.

Mapping the viruses belonging to the order Bunyavirales in China

Background:Viral pathogens belonging to the orderBunyavirales pose a continuous background threat to global health,but the fact remains that they are usually neglected and their distribution is still ambiguously known.We aim to map the geographical distribution ofBunyavirales viruses and assess the environmental suitability and transmission risk of majorBunyavirales viruses in China.Methods:We assembled data on allBunyavirales viruses detected in humans,animals and vectors from multiple sources,to update distribution maps of them across China.In addition,we predicted environmental suitability at the 10 km×10 km pixel level by applying boosted regression tree models for two importantBunyavirales viruses,including Crimean-Congo hemorrhagic fever virus(CCHFV)and Rift Valley fever virus(RVFV).Based on model-projected risks and air travel volume,the imported risk of RVFV was also estimated from its endemic areas to the cities in China.Results:Here we mapped all 89 species ofBunyavirales viruses in China from January 1951 to June 2021.Nineteen viruses were shown to infect humans,including ten species first reported as human infections.A total of 447,848 cases infected withBunyavirales viruses were reported,and hantaviruses,Dabie bandavirus and Crimean-Congo hemorrhagic fever virus(CCHFV)had the severest disease burden.Model-predicted maps showed that Xinjiang and southwestern Yunnan had the highest environmental suitability for CCHFV occurrence,mainly related toHyalomma asiaticum presence,while southern China had the highest environmental suitability for Rift Valley fever virus(RVFV)transmission all year round,mainly driven by livestock density,mean precipitation in the previous month.We further identified three cities including Guangzhou,Beijing and Shanghai,with the highest imported risk of RVFV potentially from Egypt,South Africa,Saudi Arabia and Kenya.Conclusions:A variety ofBunyavirales viruses are widely distributed in China,and the two major neglectedBunyavirales viruses including CCHFV and RVFV,both have the potential for outbreaks in local areas of China.Our study can help to promote the understanding of risk distribution and disease burden ofBunyavirales viruses in China,and the risk maps of CCHFV and RVFV occurrence are crucial to the targeted surveillance and control,especially in seasons and locations at high risk.